They are a legit company that works, at least in my area, through a platform called iSecretShop. I haven't done any jobs for them yet. iSecretShop encompasses many, many different MSCs, and Dynamic Advantage is just one of them. As long as the email wasn't about cashing any sort of check or buying gift cards, and was an invitation to do some grocery shops, it's probably very legit. Can't speak for their payment terms, but you can usually find them in the agreement you have to electronically sign on iSecretShop for Dynamic Advantage, or for ANY of the MSCs you may want to work with in that group. Good luck!